We propose to develop a room temperature, transcutaneous hydrogen sensor based upon nanoporous-titania capable of 0.1ppm hydrogen detection in the presence of potentially interfering gas analytes. We anticipate that the resulting sensor will be applied as a bandage, and be inexpensive enough to be readily used on a disposable basis. The project will build upon work of the co-investigators in the fields of high performance gas sensors, sensor electronics, and sensor integration. The specific enabling objectives to be pursued under Phase I are: {1} Extend the TiO2-nanotube hydrogen sensor fabrication technique to enable precise control over pore dimensions which in turn determine its hydrogen sensitivity. {2} Extend the anodization technique established for fabricating nanoporous TiO2 and AI203 to additional compositions including SnO2 and WO3. {3} Correlate material structures and composition with gas sensing properties, establishing algorithms for the determination of hydrogen concentration within potentially interfering gas mixtures that include CO2, O2, nitric acid, ammonia and acetone. {4} As needed, cross correlate the response of different nanoporous metal oxide sensors in an e-nose format to eliminate the effect of interfering gases enabling precise transcutaneous measurement of hydrogen, in air and at room temperature, at sub 1 ppm levels. Reduce the needed data logic processing e-nose algorithms to a commercially available data acquisition system chip (about $25) having a 2 cm x 2 cm footprint. During Phase II in collaboration with D. James Kendig of the Neonatal Intensive Care Unit at the Penn State Children's Hospital (Hershey, PA) the transcutaneous hydrogen sensor will be applied to facilitate clinical determination of the onset of neonatal necrotizing enterocolitis, a devastating disease of uncertain etiology which causes ischemia and necrosis of the small and large intestinal walls of preterm infants.